Hybrid high pressure hose

ABSTRACT

A high pressure hose and method of manufacturing the hose is disclosed. The hose is comprised of an elastomer, thermoset rubber inner tube, reinforced with one or more layers of braided or spiralized high tensile strength wire or high tenacity textile yarn and covered with a highly flexible thermoplastic sheath.

This application is a divisional application of U.S. patent applicationSer. No. 12/859,850 filed Aug. 20, 2010, which claims priority under 35USC 119 to Provisional Patent Application Ser. No. 61/236,599 filed onAug. 25, 2009. The entirety of both applications are hereby incorporatedby reference.

FIELD OF THE INVENTION

The invention is an improved hose that relates to high pressure hosesused for hydraulic actuation, high pressure spray such as high pressurewater cleaning and transfer of various liquid medium under highpressure.

BACKGROUND OF THE INVENTION

Traditionally, high pressure hoses have been made using the samematerials for the inner tube and the outer cover. In other wordselastomer or rubber hoses have been constructed using a rubber innertube and a rubber cover. So called thermoplastic or plastic hoses havebeen constructed using a thermoplastic inner tube and a thermoplasticcover.

For purposes of the present invention described herein, it is importantto provide the definitions of “rubber” and “plastic”. As used herein theterm “rubber” is synonymous with “elastomer” and refers tothermosetting, crosslinking, or curable materials, including natural andsynthetic rubbers such as, but not limited to Neoprene®, nitrile, BunaN, styrenebutadiene rubber (SBR), Hypalon™, silicone and the like.Modern elastomeric materials are often devised of more than one rubbermaterial and may contain other additives and/or be comprised ofadditional elements such as one or more thermoplastic constituent(s).

Elastomeric materials require a process of curing or vulcanization.Various methods of curing have evolved over the years and for thepurposes of this invention, conventional methods known to those familiarwith the art apply. One common method is curing in a steam autoclave.Elastomeric materials are also considered to be thermosetting, a termthat means once cured, they will not return to a liquid state.

As used herein, the term “thermoplastic” means materials which are solidat room temperature and which soften at an elevated temperaturerepeatedly. Some examples, but by no means all that may apply to thisinvention, include thermoplastic materials such as nylon, polyesterterephthalate, polyethylene, polyvinyl chloride, polyamide (nylon),ethylene vinyl acetate, polypropylene and polyurethane. Modernthermoplastic materials are often devised of more than one thermoplasticmaterial and may contain other additives and/or be comprised ofadditional elements such as one or more elastomeric or rubberconstituent(s).

As stated previously, modern polymers, whether thermoplastic orelastomeric, often contain constituents of the other. Thus, a materialis considered elastomeric if it requires curing although it may containa constituent or constituents of thermoplastic and/or other additives.Conversely, a thermoplastic material is still considered thermoplasticif it can achieve a liquid state at a certain high temperature, even ifit includes a constituent or constituents of rubber and/or otheradditives. For purposes of the present invention, materials areconsidered thermoplastic or elastomeric if they retain the processingproperties as defined herein, even if they contain components orconstituents of the other.

Wire and textile reinforced elastomeric and thermoplastic hoses areubiquitous. So much so that the Society of Automotive Engineers (SAE)has adopted detailed standards that describe the materials used in theirconstruction, dimensional tolerances and the dynamic test parameters fora wide range of hoses. Such details are amply described in the standardsSAE J343 (2004-01) and SAE J517 (2008-11). Virtually all high pressurehoses in use today are consistent with performance criteria andmaterials as described in SAE J517 and SAE J343 at least on a conceptualbasis. Design differentiation is employed when a particular nicheapplication places different demands on the hose. Such demands mayrequire a higher technical level of performance or a lower level ofperformance. In addition to the definitive U.S. standards of SAE J343and SAE J517, there are international standards, including (ISO)International Standards Organization, DIN (Deutsche Industrial Norms),BS (British Standards), EN (European Norm), and the like. All standardsare basically similar and often cross reference one another. The methodsof manufacturing the all-rubber and all-thermoplastic hoses are wellknown to those familiar with the art. Within the SAE J517 and SAE J343documents there are described three main types of high pressurehydraulic hose: steel wire braided rubber; steel wire spiralized rubberand; yarn braided thermoplastic.

U.S. Pat. No. 3,725,167 and U.S. Pat. No. 4,604,155 teach variousmethods of making steel wire braided rubber high pressure hose Suchhoses exhibit excellent flexibility, fitting retention, kink resistanceand impulse life but are known not to be as good in terms of abrasion ashoses with engineered thermoplastic cover sheaths.

U.S. Pat. No. 4,175,992 teaches various methods of making steel wirespiralized rubber high pressure hose. Such hoses exhibit excellent veryhigh pressure performance, fitting retention, kink resistance andimpulse capabilities, but because they have as many as six layers ofreinforcement are generally very stiff particularly on the larger sizes.

U.S. Pat. Nos. 3,251,381 and 3,116,760 teach various methods of makingyarn reinforced thermoplastic high pressure hoses. Such hoses exhibitexcellent high pressure performance, impulse life, and abrasionresistance, but are known to be prone to kinking and poor fittingretention problems at high temperatures particularly if the increase intemperature approaches the melt temperature of the material used ininner tube and cover sheath.

There exists a need to incorporate the best individual features of thethree basic types of hose and therefore, in recent years, variousefforts have been introduced to “hybridize” or impart features ormethods that cross over from one or more of the three concepts describedpreviously. Such attempts have only been marginally successful in nicheapplications and have often required one benefit to be sacrificed togain another.

U.S. Pat. No. 4,341,578 teaches methods to use braided wire instead ofyarn in the manufacture of thermoplastic hose. The result is improvementin fitting retention, but the hose itself remains very stiff. Suchstiffness makes the hose acceptable for a permanent installation, butfor practical purposes cannot be used as a spray hose.

In an effort to improve the known abrasion deficiencies of known rubbercovered hoses, U.S. Pat. No. 5,145,628 teaches a method whereby an ultrahigh molecular weight polyethylene (UHMWPE) is applied by wrapping atape of same over an extruded sheath covering wire braided or spiralizedrubber hose. UHMWPE is known to be very expensive even though it hassuperior abrasion resistance, which in some applications is desirable.While UHMPE is a thermoplastic material, the process requires thethermoplastic cover sheath to be applied over an extruded rubber sheathand then vulcanized.

U.S. Pat. No. 5,964,409 teaches a yarn reinforced thermoplastic hose forhigh pressure spraying whereby the inner tube and cover are producedwith highly plasticized thermoplastic materials free of a rubberconstituent. The result is an inexpensive hose, but the impulse life andtemperature resistance are dramatically below those described in SAEJ343 and SAE J517. The hose shows some improvement in flexibility, butis still relatively stiff, prone to kinking, has a low temperaturerating and is generally poor in terms of fitting retention. Such a hoseis acceptable for light duty spray applications, but would not beacceptable for hydraulic applications because of limits in temperatureand impulse life which are well below those noted in SAE J343 and SAEJ517.

U.S. Pat. No. 7,222,644 teaches a steel wire reinforced thermoplastichose for high pressure spraying whereby the inner tube and cover areproduced with highly plasticized thermoplastic materials. The result isa hose that is still very stiff although fitting retention is betterthan a textile yarn reinforced version. Again, such a hose may beacceptable for light duty spray applications, but would not beacceptable for hydraulic applications because of limits in temperatureand impulse life which are well below those noted in SAE J343 and SAEJ517.

It is generally known to those familiar with the art that wire braidedhigh pressure rubber hoses are substantially more flexible and lessprone to kinking than their thermoplastic counterparts with the sameperformance specifications as described within SAE J343 and SAE J517.For example, the performance specifications for SAE100R18 yarnreinforced thermoplastic hose are exactly the same as for SAE100R17 wirebraided rubber hose. Yet, the rubber hose is nearly impossible to kinkand remains highly flexible. U.S. Pat. No. 7,222,644 describesthermoplastic hoses with a bend radius as small as 30 mm. An equivalentwire braided all rubber hose will not kink, for example, in a nominal¼″, 5/16″ and ⅜″ (nominal inside diameter dimensions defined by SAE)size even below 30 mm if the method for measuring the bend radiusdescribed in this '644 patent is used.

On the other hand, thermoplastic hoses are known to be far superior interms of abrasion, ozone and ultraviolet light resistance by comparisonto natural and synthetic rubber compounds. An ideal hose would exhibitthe known flexibility of a reinforced rubber hose, combined with ahighly flexible, resilient thermoplastic cover.

There is therefore a need for an improved high pressure hose that meetsthe requirements of all relevant standards while combining the mostdesirable qualities of both all-elastomeric and all-thermoplastic hosesand which can be produced at a reasonable cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a portion of a hose constructedaccording to the principles of the invention, with layers partially cutaway for purposes of illustration.

FIG. 2 is a perspective view of another embodiment of a hose constructedaccording to the principles of the invention, with layers partially cutaway for purposes of illustration.

FIG. 3 is a perspective view of yet another embodiment of a hoseconstructed according to the principles of the invention, with layerspartially cut away for purposes of illustration.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

The present invention bridges the gap between elastomeric andthermoplastic high pressure hoses. Referring first to FIG. 1, a firstembodiment of the invention is illustrated in which a hose is comprisedof an inner rubber tube 10 made of an elastomeric or rubber, such asnitrile rubber. Tube 10 has an outer surface 11 and a passageway 13through which a fluid under pressure can flow. The hose also has one ormore braided or spiralized reinforcing layers 12 of textile yarn or wirecovering the outer surface of the inner tube 10, and a protectivethermoplastic sheath 14 covering the reinforcing layer 12.

To produce the hose of this first embodiment, the inner tube 10 with therubber in an uncured state is extruded over a solid steel mandrel orflexible polymeric mandrel (not shown). The tube 10 is then passedthrough a braiding machine (not shown) where high tensile strength wireis braided onto the outer surface of the tube 10 to form the reinforcinglayer 12. Such extrusion and braiding machines are well known, and thesize and type of wire and method of applying the braid to meet thedesired dynamic requirements of the hose are also well known. Atemporary thermoplastic sheath (typically Polypropylene or othersuitable material) is then applied over the outside of the reinforceduncured rubber tube 10. The uncured partially completed hose is thenplaced in a suitable autoclave where through a time controlled exposureto steam pressure, the hose is cured or vulcanized. Such curing willcreate a bond between the wire braided reinforcing layer 12 and theoutside surface 11 of the inner tube 10. Additionally, as a byproduct ofvulcanization, some of the material from the outside surface 11 of theinner tube 10 may ooze or extrude between the voids of the braiding andthe braid intersections. A small amount of material may pass through thereinforcing layer and deposit itself on the outside of the tube. This isa preferred effect. After curing, the temporary polypropylene cover isremoved preferably by means of a slitting and peeling process, andsimultaneously or separately, a flexible thermoplastic polyurethanecover 14 is extruded directly onto the exposed steel wire braidedsurface of the reinforcing layer 12. After this step, the mandrel isremoved by pressurized blow out and the hose is finished. Such a hosewill meet all dimensional, performance and dynamic requirements of SAEJ343 and SAE J517 for all types and sizes of one wire reinforced rubberhoses described in these standards. The hose of the invention willexhibit the desirable characteristics of rubber hose and all thedesirable advantages of a thermoplastic cover.

FIG. 2 illustrates the construction of a hose according to theprinciples of the invention in which two reinforcing layers areutilized. As in the previously described method for the hose of FIG. 1,the inner tube 10 with the rubber in an uncured state is extruded over asolid steel mandrel or flexible polymeric mandrel. The tube 10 is thenpassed through a braiding machine where high tensile strength wire isbraided onto the outer surface of the tube 10 to form the firstreinforcing layer 12. After the first reinforcing layer 12 is applied, athin elastomeric layer is applied 15 which is then overlaid with asecond reinforcing layer 16 of high tensile strength wire. The secondreinforcing layer 16 is spirally applied at an angle generally in anangular direction opposite to the first reinforcing layer 12. The thinelastomeric layer 15 is often referred to as a tie layer, one purpose ofwhich is to prevent the two reinforcing layers 12 and 16 from abradingagainst each other which can be detrimental to the hose service life. Atemporary thermoplastic sheath (typically Polypropylene or othersuitable material) is then applied over the outside of the doublereinforced uncured rubber tube 10. The uncured partially completed hoseis then placed in a suitable autoclave where through a time controlledexposure to steam pressure, the hose is cured or vulcanized. Such curingwill create a bond between the wire braided reinforcing layers 12 and 16and the outside surface 11 of the inner tube 10 and the tie layer 15.After curing, the temporary polypropylene cover is removed preferably bymeans of a slitting and peeling process, and simultaneously orseparately, a flexible thermoplastic polyurethane cover 14 is extrudeddirectly onto the exposed steel wire braided surface of the reinforcinglayer 16. After this step, the mandrel is removed by pressurized blowout and the hose is finished. Such a hose will meet all dimensional,performance and dynamic requirements of SAE J343 and SAE J517 for alltypes and sizes of two layer wire reinforced rubber hoses described inthese standards. The hose of the invention will exhibit the desirablecharacteristics of rubber hose and all the desirable advantages of athermoplastic cover.

FIG. 3 illustrates the construction of a hose according to theprinciples of the invention in which multiple reinforcing layers areutilized. As in the previously described methods for the hose of FIGS. 1and 2, the inner tube 10 with the rubber in an uncured state is extrudedover a solid steel mandrel or flexible polymeric mandrel. The tube 10 isthen passed through a braiding machine where high tensile strength wireis braided onto the outer surface of the tube 10 to form the firstreinforcing layer 12. After the first reinforcing layer 12 is applied, athin elastomeric layer is applied 15 which is then overlaid with asecond reinforcing layer 16 of high tensile strength wire. The secondreinforcing layer 16 is spirally applied at an angle generally in anangular direction opposite to the first reinforcing layer 12. Aspreviously mentioned, the thin elastomeric layer 15 is often referred toas a tie layer, one purpose of which is to prevent the two reinforcinglayers 12 and 16 from abrading against each other which can bedetrimental to the hose service life. Then, another tie layer 17 isapplied followed by another spirally applied reinforcing layer 18 ofhigh tensile strength wire, again in the opposite angular direction asthe preceding reinforcing layer 16. This is followed by another tielayer 19 and another spirally applied layer 20 of high tensile strengthwire, again wound in an angular direction opposite to the wire of thepreceding reinforcing layer 18. A temporary thermoplastic sheath(typically Polypropylene or other suitable material) is then appliedover the outside of the multiple reinforced uncured rubber tube 10. Theuncured partially completed hose is then placed in a suitable autoclavewhere through a time controlled exposure to steam pressure, the hose iscured or vulcanized. Such curing will create a bond between the wirebraided reinforcing layers 12, 16, 18 and 20 and the outside surface 11of the inner tube 10 and the tie layers 15, 17 and 19. After curing, thetemporary polypropylene cover is removed preferably by means of aslitting and peeling process, and simultaneously or separately, aflexible thermoplastic polyurethane cover 14 is extruded directly ontothe exposed steel wire braided surface of the last reinforcing layer 20.After this step, the mandrel is removed by pressurized blow out and thehose is finished. Such a hose will meet all dimensional, performance anddynamic requirements of SAE J343 and SAE J517 for all types and sizes ofwire reinforced multiple layer spiral rubber hoses described in thesestandards. The hose of the invention will exhibit the desirablecharacteristics of rubber hose and all the desirable advantages of athermoplastic cover.

In all of the foregoing methods described for the hoses illustrated inFIGS. 1, 2 and 3, the described steps may be done in the sequencedescribed, a different sequence or may be accomplished in a continuousprocess. And each of the hoses can also be produced by practicing thebasic steps of the following method, which is described with referenceto the hose of FIG. 1, which has a single reinforcing layer. This methodis performed by extruding the inner tube layer 10 of rubber and thenpassing the tube through a conventional continuous cure process withoutusing a mandrel. Such methods are known to those familiar with the artand may utilize microwave or infrared or some other means of curingtechnology. After curing, the inner tube 10 is braided by conventionalmeans using wire and/or textile yarn to form the reinforcing layer 12.Simultaneously, while the inner tube 10 is being braided, an adhesive isapplied to the outside surface 11 of the tube 10 between the tube andbraided material while internal pressure is applied to the internalpassageway 13 of the tube 10 so as to create an adhesive bond betweenthe tube 10 and the reinforcing layer 12 of braided material. Adhesivesfor such an application are known and may contain polyurethane solidssuspended in a solvent or may be close or open celled foaming type. Saidadhesive may ooze, flow or otherwise extrude into voids or intersectionswithin and through the reinforcement braiding and a small amount maydeposit itself on the outside of the inner tube 11. This is thepreferred effect. After the adhesive cures, the cured braided tube ispassed through a conventional extruder where a cover sheath or layer 14of thermoplastic polyurethane is applied to complete the hose. Thisembodiment of the hose of the invention will meet all dimensional,performance and dynamic requirements of SAE J343 and SAE J517 for alltypes and sizes of wire braided rubber hoses described in thesestandards. The hose will also exhibit all the desirable characteristicsof rubber hose and all the desirable advantages of hoses with athermoplastic cover.

In yet another embodiment, the hybrid hoses of the invention shown inFIGS. 1 and 2 can be formed by extruding a rubber inner tube 10 andpassing it through a conventional continuous cure process without amandrel in the same way as the preceding embodiment. In this embodiment,however, no adhesive is applied and the reinforcing layer 12 iscompleted by conventional means through braiding yarn or steel directlyonto the outer surface 11 of the inner tube 10. It may be necessary tofreeze, chill or otherwise stiffen or support the tube 10 with internalpressure so as to prevent collapse due to the tension required as partof the braiding process. To complete the hose of this embodiment, acover sheath 14 of thermoplastic is applied by a continuous extrusionprocess. The hose of this embodiment will meet all dimensional anddynamic requirements of SAE J343 and SAE J517 for all types and sizes ofwire braided rubber hoses described therein, except there will be areduction in the maximum impulse. This is because the bond between theinner tube and the reinforcement braid will result in abrasion betweenthe plies of the reinforcement layer or layers during the impulse test.In various light duty (low impulse) or high pressure spray applications,such performance would be considered acceptable. Such a trade off can beconsidered acceptable in a static application where there is no impulseand or in a high pressure spray application where the impulse frequencyis substantially below those described in SAE J343 and SAE J517.

In one test applying the principles of the invention, a nominal 5/16″(nominal inside diameter as per SAE) rubber tube was extruded onto asolid rubber mandrel, after which a wire braiding was applied byconventional means. These methods of forming the tube and applying thebraiding are consistent with the process to manufacture SAE100R1 hose asspecified in SAEJ517. The reinforced tube was wrapped spirally with anylon tape and then placed in an autoclave at high temperature in orderto vulcanize the hose. After vulcanization, the solid rubber mandrel wasremoved and a Polyurethane cover sheath was extruded onto the curedreinforced tube. This hose exhibited all the characteristics called outin SAEJ343 for testing, including: dimensional check test, proof test,change in length test, burst test, cold bend test, impulse test, leakagetest, oil resistance test, ozone resistance test, resistance to vacuumtest and volumetric expansion test.

As stated previously, a steel reinforced rubber hose is virtuallyimpossible to kink, yet remains highly flexible. It is important to notethat the prior art teaches two methods for measuring bend radius todetermine flexibility. The scope of the SAE J343 standard is toestablish a minimum bend radius, measured with the hose installed and inservice, below which bend radius a reduced service life is expected.U.S. Pat. Nos. 7,222,644 and 5,964,409 (the '644 and '409 patents) teachmethods of measuring minimum bend radius while the hose is not inservice, but rather in an unfilled, ambient pressure state, and as sodefined, minimum bend radius is the smallest radius before kinking. Tothose familiar with the art, the SAE specification is often referred toas a “dynamic” bend radius, whereas the bend radius taught in the '644and '409 patents would be considered a “mechanical” bend radius. In anyevent, the hose of the present invention meets or exceeds dynamic bendradius definitions described in both SAE standards J517 and J343 andallows for a smaller mechanical bend radius than those described in theU.S. Pat. Nos. 5,964,409 and 7,222,644.

A hose produced according to the principles of the invention asdescribed herein, when measured in accordance with the proceduresdisclosed in the U.S. Pat. Nos. 5,964,409 and 7,222,644, exhibited abend radius of 30 mm. Such results were expected as the hybrid hose ofthe present invention retains all the same basic properties of anequivalent rubber hose and is only limited by the hardness of thethermoplastic sheath material applied during the last step. A hoseconstructed according to the principles of the invention would beconsidered an acceptable product for high impulse applications such ashydraulic actuation and high pressure cleaning as well as a variety ofother high pressure applications. For high pressure cleaning, the hoseof the invention has an additional feature in that the polyurethanecover is substantially non-marking. One common complaint for the highpressure cleaning application is that a hose with a black rubber coverwill transfer rubber material to the surface, such as a driveway,swimming pool, deck or parking lot much like a spinning tire can leave avirtually permanent black mark on a street. It is well known that rubberhose producers make hoses with colored rubber compounds to offset thisphenomenon. However, it is also known that such colors serve to reducethe obviousness of mark left by the rubber transfer, but does noteliminate it. A hose covered with thermoplastic, e.g., polyurethane,requires substantially more friction before it will leave a mark, if atall, and said mark would be easily removed.

Hoses currently available in the market for high pressure cleaners usematerials similar to those used in hydraulic hoses. That is to say, theprior art teaches either a thermoplastic tube with an extrudedthermoplastic cover or a rubber hose with an extruded rubber cover. Thehose of the present invention combines the advantages of both. The '644and '409 patents both teach the use of Santoprene® a product of theDupont Company, a TPE material made by DuPont. This material exhibitsmany of the properties of rubber, including high temperaturecapabilities, and Santoprene® is rated for service of 275° Fahrenheit.However, Santoprene® is extremely expensive and although it exhibitsmany characteristics of rubber, it remains a thermoplastic material,meaning it has a specified melt point of about 350° Fahrenheit.Therefore, because of the expense and the temperature limitation, use ofSantoprene® in hoses is limited, and it is not suitable for many highpressure cleaning applications where hot water or steam applications areprevalent and thus temperatures may exceed 350° degrees Fahrenheit. Insuch applications, an all Santoprene® construction would failcatastrophically if exposed to temperatures between 275° Fahrenheit and350° Fahrenheit.

Another advantage of the present invention is that with the stability ofa high temperature resistant rubber tube, even if the thermoplasticcover used has a low melt point, such melting will not result in acatastrophic failure with the potential to cause serious injury. This isbecause the cover will simply melt, while the rubber inner tube andreinforcement will stay intact. Thus, a definite advantage of the hoseof the present invention is that it is inherently more safe than areinforced hose with a thermoplastic inner tube and thermoplastic coversheath. An intended or designed specific melt point of thermoplasticmaterial used for the cover can further be incorporated as an obvioussignal that a hose has been exposed to a temperature higher than themelt point. Such melting does not represent a hazard.

As explained in detail above, the present invention does not require anextruded rubber sheath before the thermoplastic cover is applied, whichprior art methods and hoses require. Secondly, the present inventionteaches extrusion of the thermoplastic cover rather than wrapping apre-extruded strip around the circumference of the hose. Further, thepresent invention teaches the extrusion of the thermoplastic cover as alast and separate step and is accomplished after the wire reinforcedrubber tube is vulcanized. Lastly, the present invention does notrequire the bonding of the thermoplastic to the substrate, whetherrubber or wire reinforcement.

As mentioned previously, the principal object of this invention is tocombine the most desirable features and benefits of both conventionalrubber and thermoplastic high pressure hoses. The methods of the presentinvention results in a novel hose that is virtually impossible to kinkyet remains as highly flexible as if it were entirely produced ofrubber. The hose has superior abrasion, ozone and U.V. resistance overconventional rubber hoses because the cover is produced ofthermoplastic. In addition, as a spray hose, the cover will not leaveundesirable marks as it is dragged about the surface and the hose willdemonstrate much better chemical resistance and resistance to oils andfats, especially animal fats prevalent in some high pressure cleaningenvironments. The hose maintains high temperature capabilities becausethe rubber inner tube will not melt when using a stabile thermoplasticcover. If desired, the hose can also be designed with a specific meltpoint for the cover that will indicate if the hose has been exposed to atemperature higher than the designated service temperature.

There are other advantages to the already disclosed technical advantagesof the hose of the invention. While prior art hoses establish the use ofa thermoplastic cover, as in U.S. Pat. No. 5,145,628 regarding theUHMWPE cover, such teaching describes a material that is very expensiveand is bonded to an extruded rubber cover and then passed through thevulcanization curing process. The present invention does not require thethermoplastic cover to be necessarily bonded to the outside of the wirereinforcement layer, and if such bonding is desired, it can beaccomplished through chemical adhesive means. Moreover, the presentinvention does not require that the thermoplastic cover be cured orvulcanized as part of a finished hose. Thermoplastic materials aregenerally easier to extrude than thermosetting rubber materials. Thus,if the hose is manufactured and cured without a cover, as taught by thepresent invention, the covering step can be accomplished as a last step.This allows a single hose carcass (a reinforced, cured rubber tube) tobe covered using a wide range of options. From a manufacturingperspective, this offers the flexibility of using different materialsdepending upon a specific use in a wide range of hose applications.Therefore, the hose of the present invention does not require thethermoplastic cover sheathing to withstand the very high temperaturesthat are encountered during the vulcanization process which temperaturessometimes exceed 300° Fahrenheit).

The basic principles of the invention can be applied to produce hoseswith other foreseen advantages, depending upon the particular use forwhich the hose is designed. For example, a hose may be required to use athermoplastic material capable of withstanding high temperatures.Another thermoplastic cover material may be selected on the basis ofhigh abrasion resistance. Yet another may be selected using a differentcolor or multiple colors. This allows a great degree of flexibility interms of design specificity that has not existed within the known priorart.

While the specifications and test procedures described in SAEJ343 andSAE J517 remain the definitive parameters for high pressure hose,variations in performance are anticipated. The reference to SAEJ 343 andSAE J517 does not attempt in any way to limit the invention to hoses andhose types defined therein. In contrast, the novelty of the presentinvention has appeal for a wide range of high pressure hoses used in awide variety of applications. Such variations may improve upon the basisof the descriptions described therein. Other variations may reduce theperformance dynamic to a level below for one or more of the criteriadescribed therein.

The present invention is not limited by the embodiments or examplesdescribed herein. The terms and expressions which have been used areused as terms of description and not of limitation and there is nointention in the use of such terms and expressions of excluding anyequivalents of any of the features described, or portions thereof, butit is recognized that various modifications are possible within thescope of the invention, which is defined by the following claims.

What is claimed is as follows:
 1. A method of manufacturing a highpressure hose comprising the steps of: extruding an annular tube usingan elastomeric material; applying a layer of reinforcing material aroundthe tube; applying a temporary layer of material over the reinforcingmaterial; heating the hose to a predetermined temperature and at apredetermined pressure for a period of time sufficient to cure the innertube and thereby create a bond between the inner tube and thereinforcing material; removing the temporary layer of material; andapplying a permanent thermoplastic layer over the reinforcing materialto form the finished hose.
 2. The method of manufacturing a highpressure hose of claim 1 in which the reinforcing layer is a braidedwire.
 3. The method of manufacturing a high pressure hose of claim 1 inwhich the temporary layer is a thermoplastic material.
 4. The method ofmanufacturing a high pressure hose of claim 3 in which the temporarylayer is polypropylene.
 5. The method of manufacturing a high pressurehose of claim 1 in which the heating is conducted in an autoclave. 6.The method of manufacturing a high pressure hose of claim 1 in which thepermanent thermoplastic layer is applied by extruding the layer onto thereinforcing layer.
 7. A method of manufacturing a high pressure hosecomprising the steps of: extruding an annular tube from an elastomericmaterial to form a tube having an outside surface and an innerpassageway; heating the tube to a predetermined temperature and at apredetermined pressure for a period of time sufficient to cure theelastomeric material in the tube; applying an adhesive to the outsidesurface of the tube and supporting the tube while applying a layer ofreinforcing material around the tube so as to bond the reinforcingmaterial to the tube; and extruding a cover sheath of thermoplasticmaterial over the reinforcing layer to form the finished hose.
 8. Themethod of manufacturing a high pressure hose of claim 7 in which thelayer of reinforcing material is braided wire.
 9. The method ofmanufacturing a high pressure hose of claim 8 in which the tube issupporting during the application of the reinforcing material byapplying internal pressure in the inner passageway of the tube.
 10. Amethod of manufacturing a high pressure hose comprising the steps of:extruding an annular tube from an elastomeric material to form a tubehaving an outside surface and an inner passageway; heating the tube to apredetermined temperature and at a predetermined pressure for a periodof time sufficient to cure the elastomeric material in the tube;stiffening the tube sufficiently so as to allow the application of alayer of reinforcing material around the tube; and extruding a coversheath of thermoplastic material over the reinforcing layer to form thefinished hose.
 11. The method of manufacturing a high pressure hose ofclaim 10 in which the layer of reinforcing material is braided wire. 12.The method of manufacturing a high pressure hose of claim 10 in whichthe layer of reinforcing material is braided yarn.